The aim of this thesis is to defend what is known as the primary quality view of colour. It will do this by arguing that this view better meets our conceptual schema than either of its rivals the subjectivist view or the secondary quality view. In pursuing this project, I highlight the five core beliefs (as identified by Johnston 1992) that make up our colour conceptual schema, identifying the two strongly realist beliefs as making up our prime intuition, and on these grounds I immediately reject the subjectivist stance. I then set out the primary quality view's main rival, the secondary quality view, and show how dispositionalists have argued that this view is best able to accommodate our core beliefs. However, I identify empirical findings that raise problems for the secondary quality view, revealing its inability to satisfy our extended colour concepts as well as an inability to adequately explain certain deviant cases. The core of my argument against the secondary quality view comes from what I call problems of causation, where I argue that as dispositions are not causes they are unable to meet our prime intuition, and therefore cannot be colours. I therefore set up a version of the primary quality view of colour, identifying colours with microphysical properties (or complexes thereof) and show why this view does not face the same problems of causation as the secondary quality view. I then argue that the secondary quality view does not have the advantage over the primary quality view, when it comes to the rest of our core beliefs, as its supporters would have us believe. I show how a primary quality view is able to fit all these core beliefs into our overarching colour conceptual schema, without having to appeal to the ontological extravagances that dispositionists must bestow upon colour. Finally, I address two criticisms from commonsense that are laid against the primary quality view, and argue that the primary quality view is able to meet these conceptual demands and thereby conclude that the primary quality view is the better of the putative candidates competing for capturing the ontological status of colour. / Thesis (M.A.)-University of Natal, Pietermaritzburg, 2001.

En aquest treball presentem un marc per a l'estimació del punt blanc en imatges sota condicions no calibrades, on considerem múltiples solucions interpretades. D'aquesta manera, proposem la utilització d'una cua visual que ha estat relacionada amb la constància de color: aparellament de colors. Aquest aparellament de colors està guiat per la introducció d'informació semàntica referent al contingut de la imatge. Així doncs, introduïm informació d'alt nivell dels colors que esperem trobar en les imatges. Tenint en compte aquestes dues idees, aparellament de colors i informació semàntica, i les aproximacions computacionals a la constància de color existents, proposem un mètode d'estimació de punt blanc per condicions no calibrades que lliura múltiples solucions, en funció de diferents interpretacions dels colors d'una escena. Plantegem l'extracció de múltiples solucions ja que pot permetre extreure més informació de l'escena que els algorismes clàssics de constància de color. En aquest cas, les múltiples solucions venen ponderades pel seu grau d'aparellament dels colors amb la informació semàntica introduïda. Finalment demostrem que la solució plantejada permet reduir el conjunt de solucions possibles a un conjunt més significant, que és petit i fàcilment interpretable. El nostre estudi està emmarcat en un projecte d'anotació d'imatges que pretén obtenir descriptors que representen la imatge, en concret, els descriptors de la llum de l'escena. Definim dos contextos diferents per aquest projecte: condicions calibrades, quan coneixem alguna informació del sistema d'adquisició, i condicions no calibrades, quan no coneixem res del procés d'adquisició. Si bé ens hem centrat en el cas no calibrat, pel cas calibrat hem proposat també un mètode computacional de constància de color que introdueix l'assumpció de 'món gris' relaxada per a generar un conjunt de solucions possibles més reduït. Aquest mètode té un bon rendiment, similar al dels mètodes existents, i redueix el tamany del conjunt de solucions obtingut. / In this work we present a framework for white point estimation of images under uncalibrated conditions where multiple interpretable solutions can be considered. In this way, we propose to use the colour matching visual cue that has been proved as related to colour constancy. The colour matching process is guided by the introduction of semantic information regarding the image content. Thus, we introduce high-level information of colours we expect to find in the images. Considering these two ideas, colour matching and semantic information, and existing computational colour constancy approaches, we propose a white point estimation method for uncalibrated conditions which delivers multiple solutions according to different interpretations of the colours in a scene. However, we present the selection of multiple solutions which enables to obtain more information of the scene than existing colour constancy methods, which normally select a unique solution. In this case, the multiple solutions are weighted by the degree of colour matching between colours in the image and semantic information introduced. Finally, we prove that the feasible set of solutions can be reduced to a smaller and more significant set with a semantic interpretation. Our study is framed in a global image annotation project which aims to obtain descriptors which depict the image, in this work we focus on illuminant descriptors.We define two different sets of conditions for this project: (a) calibrated conditions, when we have some information about the acquisition process and (b) uncalibrated conditions, when we do not know the acquisition process. Although we have focused on the uncalibrated case, for calibrated conditions we also propose a colour constancy method which introduces the relaxed grey-world assumption to produce a reduced feasible set of solutions. This method delivers good performance similar to existing methods and reduces the size of the feasible set obtained.

Much research suggests that there exist universal colour names. Investigations involving paint and paper media have revealed co-incidence of especially salient names and their concomitant sensations, within and between cultures. These names have been called Basic Colour Terms (BCfs), and their prototypical sensations focal colours (or foci). The highest levelof colour name development within cultures includes eleven BCfs. A literature review revealed certain omissions in the colour naming work. Firstly was a lack of usage of CRT-baseddisplay of colours. This was considered an important omission given the implicit, but largely untested assumption that CRT and surface media may be equivalent. A second omission identified was a lack of detailed quantification of realistic naming behaviour. Two CRT-based experiments were then devised to quantify colour naming, one involving unconstrained naming of colours, one involving selection of which colours were exemplars of (thirteen) pre-generated colour names. These experiments revealed certain regularities in naming within a (perceptually uniform) colour space. Thus a naming space and its underlying structure was obtained. Naming space was found to be a composite of they way membership of (BCf) categories was expressed, and an underlying set of five fundamental colour sensations. Evidencewas then forthcoming that this structure might be modelable. The quantified data obtained was then used to investigate the search-efficacy of easy to name colours. Such easy to name palettes were generated, based on the data obtained, and compared with colorimetrically matched, and highly discriminable palettes. It was found that easy to name as a colour palette variable was meaningful, and capable of adjusting user performance, despite evidence that individuals may possess relatively stable, idiosyncratic colour vocabularies. That CRT work has generality was verified by comparison of foci obtained from a series of studies involving different media. Although some differences were evident, these followed clear patterns which were not inconsistent with universal colour naming. This thesis suggests that there exist complex aspects of colour naming behaviour which are nevertheless understandable, and largely predictable. Such theoretical data should allow for improvements in certain human-interactions, where tasks involve naming colours.

Published Article / The main objective of this paper is to point out the crucial role that colour plays in human perception of stimuli, and how we may use this information to promote and enhance our communicational objectives. If we can educate consumers to use colour codes at the point of purchase, we will assist them to make the best purchasing decision and in the end save the consumer money.

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

Greenfinch plumage varies both between and within age and sex classes. This study looked at the possible causes and consequences of this variation in a colour-ringed population. Plumage colour was both repeatable and heritable. The function of colourful plumage in the breeding season was reviewed. Many aspects of the breeding biology of Greenfinches were studied and the effects of plumage on breeding success investigated. Brightly coloured birds seemed to have greater reproductive success than dull ones. Brightly coloured males were also more likely to ret urn to the study area in the following breeding season. Greenfinches are usually regarded as monogamous, but I found that over 25% of nests involved polygamy. Polygyny, polyandry and possible cases of polygynandry were recorded, but polygyny was the most common of the three. It was demonstrated that the experimental provision of food influenced the occurrence of polygyny. The literature generally considers polygyny to be bad for females, however in Greenfinches polygynous pairs were as successful at producing independent offspring as monogamous pairs. Polygynous birds recruited more offspring into the local population than monogamous birds, although this may reflect differences in dispersal. Since polygynous males were bright and had better survival and since colour was found to be heritable, females may have been choosing males for their good genes. If colour is an honest signal, there must be some cost preventing dull birds from becoming bright. Bright Greenfinches were more likely to be killed by Sparrowhawks during the summer than dull Greenfinches and they were also more likely to be injured. In comparison, dull birds were more likely to be killed by Tawny Owls in the winter. Whether Greenfinch plumage variation acted as a "badge of status" over the winter was investigated. The brighter a Greenfinch's plumage the more likely it was to win confrontations at a bird table in the winter, regardless of food type (contra Maynard Smith & Harper 1988). So what influenced a Greenfinch's plumage? Birds with damaged feathers only regrew bright plumage if they were in good body condition. Birds with low fat stores regrew paler feathers after damage, which is possibly related to the fact that the carotenoid pigment is stored in fat. Therefore, it is possible that after the breeding season good quality nales recovered faster, put on more fat and acquired brighter plumage in the moult. Plumage variation in the House Sparrow was also investigated. In hand estimates of bib size were correlated with spectrophotometric estimates of melanin content. Bib size was not related to organ size. The results of this study are compared with the literature on status signalling . It is argued that badges are handicaps i.e. uncheatable signals of individual quality, rather than being arbitrary signals or signalling Resource Holding Potential.

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